AAVSO Alert Notice 437

Campaign to monitor the recurrent nova T Pyx throughout 2011 eruption

April 15, 2011: Further to AAVSO Alert Notice 436[1], a fast photometry observing campaign has been initiated by Dr. Bradley Schaefer (Louisiana State University) to monitor the recurrent nova T Pyxidis throughout its current eruption.

Brief summary of eruption: The recurrent nova T Pyx was discovered in outburst by M. Linnolt (Hawaii, United States) at visual magnitude 13.0 on 2011 April 14.2931 (JD 2455665.7931), and confirmed by A. Plummer (Linden, NSW, Australia) at visual magnitude 12.2 on April 14.3847 (JD 2455665.8847) and S. Kerr (Glenlee, QLD, Australia) at visual magnitude 11.3 on April 14.4410 (JD 2455665.9410). This is the first outburst of T Pyx since December 7, 1966, nearly 45 years ago. As of April 15.6271 (JD 2455667.12708), it had brightened to visual magnitude 8.3 (A. Pearce, Nedlands, WA, Australia). If it behaves as in past eruptions, it can be expected to brighten to magnitude 6. All observations -- visual, CCD, and PEP observations, and CCD time series -- are encouraged.

Campaign: Full details of the campaign may be found on the T Pyx campaign information page[2]. The following is a description of the campaign summarized from that page:

"The goal is to obtain nearly-fulltime coverage of T Pyx with time resolution of minutes throughout the entire eruption up until T Pyx is lost behind the Sun around the start of August. This will require many observers, widely spaced around the world, each taking long runs of CCD images. The eruption takes roughly 9 months to go back to quiescence, but we will only go from now until the end of July (3.5 months) when T Pyx is lost behind the Sun.

"...V filter is preferred for CCD observations, with second choice being B filter, third choice R, and last choice unfiltered. (T Pyx should be magnitude 6-10 over this whole time interval, so a filter will help against saturation.) To make for a uniform magnitude scale by everyone, please use the following comparison stars:

Please use the COMPARISON star (AAVSO="93") for all the differential photometry as it will have nearly the same colors as T Pyx. Use the other backup comparison stars only if you have troubles with field size, saturation, or SNR problems. With the bright stars and differential photometry, T Pyx can be followed down low on the horizon.
"T Pyx is only one of ten known recurrent novae in our own Milky Way galaxy. It has erupted in 1890, 1902, 1920, 1944, and 1967...we...are not missing any eruptions in this time interval...Judging from the 1967 eruption light curve, the current eruption light curve will stall out of its rise at around V=8 around 15 April, slowly rise to a peak near V=6.4 around 20 May, slowly fade to V=10 by middle August, then have a sudden drop by two magnitudes over the next 20 days (with drop being invisible due to the Sun)...
"Recurrent novae...are one of the best candidate systems for being the progenitor of Type Ia supernova. This progenitor problem is a long standing sore mystery...Indeed, in last year's Decadal Survey, the National Academy of Sciences identified the progenitor problem one of the four most important problems in all astronomy...T Pyx...[is] the lynchpin of many arguments and discussions for the progenitor problem. The work on this eruption will largely be aimed at testing whether T Pyx will become a Type Ia supernova.
"...Only one nova has large amounts of fast photometry...the recurrent nova U Sco, which erupted in 2010. For this, I organized a large worldwide collaboration of (mostly amateur) observers, and we measured 37,000 magnitudes..With this awesome data set, we discovered two completely new phenomena...who knows what more will be discovered for the second very-well-observed nova.
"I envision a repeat of the wildly successful U Sco worldwide collaboration of astronomers, so that we can get very detailed light curves of T Pyx and all its expected-complicated variations throughout the eruption. The goal is to follow all the big and subtle variations in exquisite detail so that we can understand their causes...All contributing observers will be included as authors of the resulting papers..."